1. Field of the Invention
The present invention relates to a thin film magnetic head having at least an inductive-type magnetic transducer for writing and to a method of manufacturing the same.
2. Description of the Related Art
Recently, an improvement in performance of thin film magnetic heads has been sought in accordance with an increase in a surface recording density of a hard disk drive. A composite thin film magnetic head, which has a stacked structure of a recording head having an inductive-type magnetic transducer for writing and a reproducing head having a magnetoresistive effect element (hereinafter referred to as an MR element) for reading-out, is widely used as the thin film magnetic head. MR elements include an AMR element using a magnetic film exhibiting an anisotropic magnetoresistive effect (hereinafter referred to as an AMR effect) and a GMR element using a magnetic film exhibiting a giant magnetoresistive effect (hereinafter referred to as a GMR effect). The reproducing head using the AMR element is called an AMR head or simply an MR head, and the reproducing head using the GMR element is called a GMR head. The AMR head is used as the reproducing head whose surface recording density exceeds 1 gigabit per square inch, and the GMR head is used as the reproducing head whose surface recording density exceeds 3 gigabits per square inch.
In general, an AMR film is made of a magnetic substance that exhibits the MR effect and has a single-layered structure. In contrast, many of the GMR films have a multi-layered structure consisting of a plurality of films. There are several types of producing mechanisms of the GMR effect. The layer structure of the GMR film depends on the mechanism. A super lattice GMR film, a spin valve film, a granular m and the like are proposed as the GMR film. Of these types of films, the spin valve film is most efficient as the GMR film which is relatively simple in structure, exhibits a great change in resistance in a low magnetic field, and is suitable for mass-production.
A pattern width, especially an MR height is a primary factor for determining the performance of a reproducing head. The MR height is the length (height) between the end of the MR element closer to an air bearing surface and the other end. The MR height is originally controlled by the amount of polishing during the process of the air bearing surface. The air bearing surface (ABS) is a surface of a thin film magnetic head facing a magnetic recording medium and is also called a track surface.
An improvement in performance of a recording head has also been expected in accordance with the improvement in performance of a reproducing head. It is necessary to increase the track density of the magnetic recording medium in order to increase the recording density among the performance of the recording head. In order to achieve this, it is necessary to develop the recording head with a narrow track structure, the width of a bottom magnetic pole (bottom pole) and a top magnetic pole (top pole) sandwiching a write gap on the air bearing surface being reduced to the order of several microns to submicron. The semiconductor process technique is used to achieve the narrow track structure.
The throat height (TH) is another factor for determining the performance of the recording head. The throat height is the length (height) between the air bearing surface and an edge of an insulating layer (magnetic pole portion) which electrically isolates the thin film coil. Reducing the throat height is desired in order to improve the performance of the recording head. The throat height is also controlled by the amount of polishing during the process of the air bearing surface.
In order to improve the performance of the thin film magnetic head, it is important to form the recording head and the reproducing head in well balance.
An example of a method of manufacturing a composite thin film magnetic head will be described with reference to FIGS. 26A and 26B through FIGS. 31A and 31B as an example of a thin film magnetic head of the related art.
As shown in FIGS. 26A and 26B, an insulating layer 202 made of, for example, alumina (aluminum oxide, Al2O3) is formed with about 5 to 10 xcexcm thick on a substrate 201 made of, for example, altic (Al2O3. TiC). Subsequently, a bottom shield layer 203 for the reproducing head made of, for example, permalloy (NiFe) is formed on the insulating layer 202.
As shown in FIGS. 27A and 27B, for example, alumina of about 100-200 nm in thickness is deposited on the bottom shield layer 203 to form a shield gap film 204. An MR film 205 of tens of nanometers in thickness for making up the MR element for reproducing is formed on the shield gap film 204, and high-precision photolithography is applied to obtain a desired shape. A lead terminal layer 206 for the MR film 205 is formed by lift-off. A shield gap film 207 is formed on the shield gap film 204, the MR film 205 and the lead terminal layer 206, and the MR film 205 and the lead terminal layer 206 are buried in the shield gap films 204 and 207. A top shield-cum-bottom pole (hereinafter referred to as a bottom pole) 208 of about 3 xcexcm in film thickness made of a magnetic material used for both the reproducing head and the recording head such as permalloy (NiFe) is formed on the shield gap film 207.
As shown in FIGS. 28A and 28B, a write gap layer 209 of about 200 nm in film thickness made of an insulating layer such as an alumina film is formed on the bottom pole 208. Further, an opening 209a for connecting the top pole and the bottom pole is formed through patterning the write gap layer 209 by photolithography. A pole tip 210 is formed of the magnetic materials consisting of permalloy (NiFe) and nitride ferrous (FeN) through plating with a connecting portion pattern 210a for connecting the top pole and the bottom pole. The bottom pole 208 and a top pole layer 216 which will be described hereinafter are connected by the connecting portion pattern 210a and therefore forming a through hole after CMP (Chemical and Mechanical Polishing) process, which will be described later, becomes easier.
As shown in FIGS. 29A and 29B, the write gap layer 209 and the bottom pole 208 are etched about 0.3 to 0.5 xcexcm by ion milling having the pole tip 210 as a mask. By etching to the bottom pole 208, a trim structure is formed. As a result, the widening of effective write track width can be avoided (that is, suppressing the spread of magnetic flux in the bottom pole when data is being written). Subsequently, after an insulating layer 111 with a film thickness of about 3 xcexcm, made of, for example, alumina is formed over the whole surface and then the surface is planarized by CMP.
As shown in FIGS. 30A and 30B, a thin film coil 212 of a first layer for an inductive-type recording head made of, for example, copper (Cu) is selectively formed on the insulating layer 211 by, for example, plating. On the insulating layer 211 and the thin film coil 212, a photoresist film 213 is formed in a desired pattern by high-precision photolithography. A heat treatment of a predetermined temperature is applied to planarize the photoresist film 213 and to insulate between the turns of the thin film coil 212. Similarly, a thin film coil 214 of a second layer and a photoresist film 215 are formed on the photoresist film 213, and the heat treatment of a predetermined temperature is applied to planarize the photoresist film 215 and to insulate between the turns of the thin film coil 214.
As shown in FIGS. 31A and 31B, a top yoke-cum-top pole layer (hereinafter referred to as a top pole layer) 216 made of the magnetic material for recording heads, for example, permalloy is formed on the pole tip 210 and the photoresist films 213 and 215. The top pole layer 216 is in contact with the bottom pole 208 in a rearward position of the thin film coils 212 and 214, and magnetically coupled to the bottom pole 208. On the top pole layer 216, an overcoat layer 217 made of, for example, alumina is formed. At last, a track surface (air bearing surface) 218 for the recording heads and the reproducing heads is formed through processing a slider, and then a thin film magnetic head is completed. In FIGS. 31A and 31B, TH indicates the throat height, MR-H indicates the MR height, and P2W indicates the track (magnetic pole) width.
An apex angle indicated with xcex8 in FIG. 31A is a factor for determining the performance of the thin film magnetic head besides the throat height TH, the MR height MR-H, and so on. The apex angle is an angle between the straight line connecting the corners of sides on the track surface sides of the photoresist films 213 and 215, and the top surface of the top pole layer 216.
In order to improve the performance of the thin film magnetic head, it is important to form the throat height TH, the MR height MR-H, the apex angle xcex8 and the track width P2W shown in FIG. 31A, precisely.
Especially in recent years, the track width PW2 with submicron dimension equal to or less than 1.0 xcexcm is required to enable high surface density recording, that is, to form a narrow track structured recording head. Therefore, a technique of processing the top pole to submicron dimension using a semiconductor processing technique is required. Also, the magnetic pole using the magnetic materials having higher saturation magnetic flux density is desired in accordance with being the narrow track structure.
The problem is that it is difficult to scale down the top pole layer 216 formed on a coil area (apex area) being protruded like a mountain covered with the photoresist films (for example, the photoresist films 213 and 215 shown in FIG. 31A.)
As a method of forming the top pole, the frame plating, as disclosed in, for example, Japanese Patent Application laid-open in Hei 7-262519, is used. When the top pole is formed by the frame plating, first, a thin electrode film made of, for example, permalloy is formed all over the apex area. Secondly, a photoresist is applied on the apex area, and by patterning it through photolithography, a frame for plating is formed. At last, the top pole is formed through plating using the electrode film formed earlier as a seed layer.
The apex area has differences in height, for example, equal to or more than 7 to 10 xcexcm. If the film thickness of the photoresist formed on the apex area is required at least 3 xcexcm, a photoresist film of equal to or more than 8 to 10 xcexcm in thickness is formed in the lower part of the apex area since the photoresist with liquidity gathers into a lower area. In order to form a narrow track as described, a pattern with submicron width is required to be formed with a photoresist film. Accordingly, it is necessary to scale down the pattern with submicron width with a photoresist film of equal to or more than 8 to 10 xcexcm in thickness, however, it has been extremely difficult.
Moreover, during an exposure of photolithography, a light for the exposure reflects by the electrode film made of, for example, permaloy, and the photoresist is also exposed by the reflecting light causing deformation of the photoresist pattern and so on. As a result, the side walls of the top pole take a rounded shape and so on, and the top pole can not be formed in a desired shape. As described, with a related art, it has been extremely difficult to precisely control the track P2W and to form the top pole precisely so as to have the narrow track structure.
As shown in the steps in FIGS. 28A and 28B through 31A and 31B, a method of connecting the pole tip 210 and the yoke-cum-top pole layer 216 after forming a track width of equal to or less than 1.0 xcexcm in the pole tip 210 which is effective for forming the narrow track of the recording head. Namely, a method of dividing the regular top pole into the pole tip 210 for determining the track width and the top pole layer 116 which becomes the yoke area for inducing magnetic flux is employed (Ref. Japanese Patent Application laid-open Sho 62-245509, and Sho 60-10409). By dividing the top pole into two as described, microfabrication of one of the pole tip 210 on a flat surface of the write gap layer 209 is possible with sub micron width.
How ever, the problems as follows regarding the thin film magnetic head have still existed.
(1) First, in the magnetic head of the related art, the throat height is determined in the end of a further side from the track surface 218 of the pole tip 210. If the width of the pole tip 210 becomes narrower, the pattern edge is formed in a rounded shape by photolithography. Therefore, the throat height, which is required to have a highly precise dimension, is not formed to be uniform. As a result, the track width of the magnetoresistive element unbalanced in the steps of processing and polishing of the track surface. If the track width of 0.5 to 0.6 xcexcm is required, for example, the end of a further side from the track surface 218 of the pole tip 210 shifts from the throat height zero position to the track surface side and writing gap is widely opened. This causes the problem that the recording data cannot be written.
(2) As described above, in the magnetic head of the related art, it is not necessary to scale down the top pole layer 216 as minute as the pole tip 210, because the track width of the recording head is determined by the pole tip 210 which is one of the top pole being divided into two. However, since the position of the top pole layer 216 is determined in the upper area of the pole tip 210 by positioning of photolithography, if both the top pole layer 216 and the pole tip 210 are largely shifted to one side when viewed from the track surface 218 (FIG. 31A) side, so-called side write for performing the writing on the top pole layer 216 side occurs. As a result, the effective track width is widened and the data is written in a region other than the original data recording region in a hard disk.
Further, if the track width of the recording head is extremely scaled down, especially equal to or less than 0.5 xcexcm, the precise process in submicron width is required for the top pole layer 216. If the difference in width of the pole tip 210 and the top pole layer 216 is too significant in the lateral direction viewed from the track surface 218 (FIG. 31A) side, the side write occurs, as described above. This causes the problem that the data is written in a region other than the original data recording region in the hard disk.
Accordingly, the pole tip 210 as well as the top pole layer 216 are required to be processed in the submicron width. However, microfabrication of the top pole layer 116 is difficult because of the significant difference in height in the apex area under the top pole layer 216 as described above.
(3) Moreover, it is difficult for the magnetic head of the related art to shorten a yoke length. The narrower the coil pitch becomes, the easier the achievement of a head with short yoke length becomes and, especially, the recording head with a high frequency characteristics can be formed. However, when the coil pitch is made smaller and smaller, the distance from the throat height zero position to the outer circumferential end of the coil becomes a main factor for preventing the yoke length from shortening. The two-layered coil can shorten the yoke length than the one-layered coil so that many of the recording heads for high frequency employ the two-layered coil. However, in the magnetic head of the related art, after forming a first layer of the coil, a photoresist film of about 2 xcexcm thick is formed in order to form an insulating layer between the turns of the coil. Therefore, a small apex area having the rounded shape is formed in the outer circumferential end of the first layer of the coil. Next, a second layer of the coil is formed thereon. In this time, the seed layer for forming the second layer of the coil can not be etched in the slope of the apex area result in short-circuit of the coil, which makes it impossible to form the second layer of the coil. Accordingly, the second layer of the coil is required to be formed on a flat area. When the slope of the apex area is 45 to 55xc2x0, if a thickness of the coil is 2 to 3 xcexcm and a thickness of the insulating film between the turns of the coil is 2 xcexcm, the distance from the outer circumferential end of the coil to the vicinity of the throat height zero position is required to be 8 to 10 xcexcm which is twice of 4 to 5 xcexcm, (the distance from the contact area of the top pole and the bottom pole to the outer circumferential end of the coil is also required to be 4 to 5 xcexcm). This has been the main factor for preventing the yoke length from shortening. For instance, when forming the 11 turns-two-layered coil with line/space being 1.0 xcexcm/1.0 xcexcm, suppose the first layer is 6 turns and the second layer is 5 turns, then the length of the coil of the yoke length is 11 xcexcm. In this case, since the distance of 8 to 10 xcexcm is required in the apex area of the outer circumferential end, shortening of the yoke length of equal to less than 19 to 21 xcexcm is impossible. This has prevented the high frequency characteristics from improving.
The applicant has proposed the thin film magnetic head which can precisely control the throat height of the recording head and enable the super-microfabrication of the top pole layer and the pole tip in submicron width and further shortened the yoke length of the recording head (Japanese Patent Application laid-open Hei 7-243942). In this magnetic head, the bottom pole is also divided into a flat bottom pole layer (bottom pole) and a bottom pole tip like the top pole. The bottom pole tip is formed being protruded shape against the bottom pole layer and the insulating layer made of inorganic materials is formed adjacent to the bottom pole tip. This magnetic head allows to determine the throat height precisely by making the length from the surface of the bottom pole tip facing the recording medium to the inner direction equal to the length of the throat height of the recording head.
The object of the invention is to provide a preferred method of manufacturing the thin magnetic head which is easy to manufacture the thin magnetic head proposed in above mentioned application, that is, the thin magnetic head having the structure that the magnetic pole and the insulating layer lie contiguously and determine the throat height of the recording head precisely.
The another object of the invention is to provide the thin magnetic head which enable the shortening of the yoke length of the recording head.
A method of manufacturing the thin film magnetic head of the invention having at least two magnetic layers including two magnetic poles being magnetically coupled to each other, part of sides of which facing the recording medium face each other sandwiching a write gap layer, and one or more than two layers of the thin film coil for generating magnetic flux, include the steps of: selectively forming the insulating layers having a reversed pattern shape to the magnetic pole on the magnetic layer after forming the planarized magnetic layer; and forming the magnetic pole magnetically coupled to part of the magnetic layer by using the pattern of the insulating layer.
Specifically, the insulating layer having the reversed pattern shape to the magnetic pole is selectively formed on the magnetic layer and the magnetic material is deposited on the insulating layer and the magnetic layer, and then the magnetic pole which is magnetically coupled to part of the magnetic layer is formed by planarization being the same height as the surface of the insulating layer.
In the method of manufacturing the thin film magnetic head, a magnetic pole is formed to be adjacent to the insulating layer by planarizing the magnetic layer using the insulating layer formed earlier. As a result, the throat height of the recording head is determined precisely by making the distance of the end surface of the insulating layer from the surface of the magnetic pole facing the recording medium (that is, the length from the surface of the magnetic pole facing the recording medium to the inner direction) is equal to the length of the throat height of the recording head.
Another method of manufacturing the thin film magnetic head of the invention having at least two magnetic layers including two magnetic poles being magnetically coupled to each other, part of sides of which facing the recording medium face each other sandwiching the write gap layer, and one or more than two layers of the thin film coil for generating magnetic flux, includes the steps of: forming a first insulating layer on the magnetic layer after planarizing the magnetic layer; forming a thin film coil on the first insulating layer and then forming a second insulating layer to cover the thin film coil; patterning the first and the second insulating layers to be the reversed pattern shape to the magnetic pole; and forming a magnetic pole to be magnetically coupled to part of the magnetic layer by using the patterns of the first and the second insulating layers.
Specifically, the magnetic pole which is magnetically coupled to part of the magnetic layer is formed by planarization being the same height as a surface of the second insulating layer after patterning the first and the second insulating layers and depositing the magnetic material on the magnetic layer and the second insulating layer.
Also in the method of manufacturing the thin film magnetic head, the magnetic pole is formed to be adjacent to the insulating layer by planarizing the magnetic layer using the first and the second insulating layers patterned earlier. As a result, the throat height of the recording head is determined precisely by making the distance of the end surfaces of the first and the second insulating layers from the surface of the magnetic pole facing the recording medium (that is, the length from the surface of the pole tip facing the recording medium to the inner direction) is equal to the length of the throat height of the recording head.
A thin film magnetic head of the invention comprises two magnetic layers, each of which has at least one or more layers, including two magnetic poles being magnetically coupled to each other, part of sides of which facing the recording medium face each other sandwiching the write gap layer, and a inductive-type magnetic transducer having the thin film coil disposed between the magnetic layers with insulated, wherein the one magnetic layer has a first portion located in the region including the interior region face to the whole thin film coil, a second portion forming the magnetic pole and being connected to the first portion, and a third portion for connecting the first portion and the other magnetic layer; and at least part of the thin film coil is located to face to the first portion and to pass through between the second and the third portions.
In the thin film magnetic head of the invention, the second portion of one magnetic layer may determines the throat height.
In the thin film magnetic head of the invention, the other magnetic layer may have a first portion located in the region including the interior region face to the thin film coil, a second portion forming the magnetic pole and being connected to the first portion, and a third portion for connecting the first portion and one magnetic layer.
In the thin film magnetic head of the invention, the end surface of the first portion of the other magnetic layer facing the recording medium may be located far from the surface facing the recording medium of the thin film magnetic head.
In the thin film magnetic head of the invention, the length of the second portion of the other magnetic layer may be equal to or more than twice as the length of the second portion of one magnetic layer.
In the thin film magnetic head of the invention, the thin film coil may have a first layer located to pass through between the second and the third portions of one magnetic layer, and a second layer located to pass thorough between the second and the third portions of the other magnetic layer.
In the thin film magnetic head of the invention may comprises: a magnetic transducer; and a first and a second shield layers for shielding the magnetic transducer located to be face each part of the sides of the shield layers facing the recording medium sandwiching the magnetic transducer. In this case, the second shield layer also may serves as one magnetic layer.
Other and further objects, features and advantages of the invention will appear more fully from the following description.